Method for transmitting control signal for MBMS data in wireless mobile communication system

ABSTRACT

A method for transmitting a control signal for multimedia service data of UMTS (Universal Mobile Telecommunications System) includes MBMS service data that can be transmitted in a wireless system providing various types of MBMS service. An MBMS scheduling block including an MBMS service identifier list and scheduling information of MBMS RB set information and an MBMS service information block including one MBMS service identifier and MBMS RB set information for a corresponding service are transmitted to a terminal group.

[0001] This application claims the benefit of the Korean Application No.P2002-48262 filed on Aug. 14, 2002, which is hereby incorporated byreference for all purposes as if fully set forth herein.

BACKGROUND OF THE INVENTION

[0002] 1. Field of the Invention

[0003] The present invention relates to a multimedia broadcast/multicastservice (MBMS) and, more particularly, to a method for transmitting acontrol signal for transmission of MBMS data in a universal mobiletelecommunications system (UMTS).

[0004] 2. Discussion of the Related Art

[0005] A universal mobile telecommunications system (UMTS) is a thirdgeneration mobile communication system that has evolved from a standardknown as Global System for Mobile communications (GSM). This standard isa European standard which aims to provide an improved mobilecommunication service based on a GSM core network and wideband codedivision multiple access (W-CDMA) technology.

[0006]FIG. 1 shows a network structure of a general UMTS.

[0007] As shown in FIG. 1, the UMTS is roughly divided into a terminal,a UTRAN and a core network.

[0008] The UTRAN includes one or more radio network sub-systems (RNS).Each RNS includes an RNC and one or more Node Bs managed by the RNCs.

[0009] Node Bs are managed by the RNCs, receive information sent by thephysical layer of a terminal (e.g., mobile station, user equipmentand/or subscriber unit) through an uplink, and transmit data to aterminal through a downlink. Node Bs, thus, operate as access points ofthe UTRAN for terminal.

[0010] The RNCs perform functions which include assigning and managingradio resources, and operate as an access point with respect to the corenetwork.

[0011] A primary function of UTRAN is constructing and maintaining aradio access bearer (RAB) for a call connection between the terminal andthe core network. The core network applies quality of service (QoS)requirements of end-to-end to the RAB, and accordingly, UTRAN cansatisfy the QoS requirements of the end-to-end by constructing andmaintaining the RAB.

[0012] The RAB service is divided into an Iu bearer service and a radiobearer service of a lower concept. The Iu bearer service handlesreliable user data transmission between boundary nodes of UTRAN and thecore network, while the radio bearer service handles reliable user datatransmission between the terminal and UTRAN.

[0013]FIG. 2 illustrates a radio protocol between the terminal and UTRANon the basis of the 3GPP wireless access network standards.

[0014] With reference to FIG. 2, the radio protocol is vertically formedof a physical layer, a data link layer and a network layer, and ishorizontally divided into a user plane for transmitting data informationand a control plane for transmitting a control signal.

[0015] The user plane is a region to which traffic information of a usersuch as voice or an IP packet is transmitted. The control plane is aregion to which control information such as an interface of a network ormaintenance and management of a call is transmitted.

[0016] In FIG. 2, protocol layers can be divided into a first layer(L1), a second layer (L2) and a third layer (L3) based on three lowerlayers of an open system interconnection (OSI) standard model well knownin a communication system.

[0017] The first layer (PHY) provides an information transfer service tothe upper layer by using various radio transfer techniques.

[0018] The first layer is connected to the MAC layer through a transportchannel, and data is transferred between the MAC layer and the PHY layerthrough the transport channel.

[0019] Data is transmitted according to transmission time interval (TTI)through the transport channel. The physical channel transfers data bydividing it by the unit of certain time called a frame. In order tosynchronize the transport channel between the UE and UTRAN, a connectionframe number (CFN) is used. The CFN value has the range of 0˜255 in caseof transport channels except for a paging channel (PCH). That is, CFN isrepeatedly circulated by the period of 256 frames.

[0020] Besides the CFN, a system frame number (SFN) is also used tosynchronize the physical channel. The SFN value has the range of 0˜4095and repeated by the period of 4096 frames.

[0021] The MAC layer provides a re-allocation service of the MACparameter for allocation and re-allocation of radio resources.

[0022] The MAC layer is connected to the radio link control (RLC) layerthrough a logical channel, and various logical channels are providedaccording to the kind of transmitted information. In general, wheninformation of the control plane is transmitted, a control channel isused. When information of the user plane is transmitted, a trafficchannel is used.

[0023] The MAC is classified into an MAC-b sublayer, an MAC-d sublayerand an MAC-c/sh sublayer according to types of managed transportchannels. The MAC-b sublayer manages a BCH (Broadcast Channel) handlingbroadcast of system information, while the MAC-c/sh sublayer managesshared transport channel such as FACH (Forward Access Channel), DSCH(Downlink Shared Channel), or the like, shared with other terminals.

[0024] In UTRAN, the MAC-c/sh sublayer is positioned at a control RNC(CRNC) and manages channels shared by every terminal in a cell, so thatone MAC-c/sh sublayer exists in each cell.

[0025] The MAC-d sublayer manages a DCH (Dedicated Channel), a dedicatedtransport channel for a specific terminal. Accordingly, the MAC-dsublayer is positioned at a serving RNC (SRNC) managing a correspondingterminal, and one MAC-d sublayer exists also at each terminal.

[0026] A radio link control (RLC) layer supports a reliable datatransmission and may perform a function of segmentation andconcatenation of an RLC service data unit (SDU) coming from a higherlayer. The RLC SDU transferred from the higher layer is adjusted in itssize according to a throughput capacity at the RLC layer, to whichheader information is added, and then transferred in a form of a PDU(Protocol Data Unit) to the MAC layer. The RLC layer includes an RLCbuffer for storing the RLC SDU or the RLC PDU coming from the higherlayer.

[0027] A broadcast/multicast control (BMC) layer performs functions ofscheduling a cell broadcast message (CB) transferred from the corenetwork and broadcasting the CB to UEs positioned in a specific cell(s).At the side of UTRAN, the CB message transferred from the upper layer iscombined with information, such as a message ID, a serial number or acoding scheme, and transferred in a form of BMC message to the RLC layerand to the MAC layer through a CTCH (Common Traffic Channel), a logicalchannel. In this case, the logical channel CTCH is mapped to a FACH(Forward Access Channel), a transport channel, and an S-CCPCH (SecondaryCommon Control Physical Channel), a physical channel.

[0028] A packet data convergence protocol (PDCP) layer is an upper layerof the RLC layer, allowing data to be transmitted effectively on a radiointerface with a relatively small bandwidth through a network protocolsuch as the IPv4 or the IPv6. For this purpose, the PDCP layer performsa function of reducing unnecessary control information, which is calleda header compression, and in this respect, RFC2507 and RFC3095 (robustheader compression: ROHC), a header compression technique defined by anInternet standardization group called an IETF (Internet Engineering TaskForce), can be used. In these methods, because the only informationrequisite for the header part of a data is transmitted, controlinformation is transmitted, so that an amount of data transmission canbe reduced.

[0029] The RRC layer positioned in the lowest portion of the third layer(L3) is defined only in the control plane and controls the logicalchannels, the transport channels, and the physical channels in relationto the setup, the reconfiguration, and the release of the RBs. The RBsignifies a service provided by the second layer for data transmissionbetween the terminal and UTRAN, and setting up the RB means processes ofstipulating the characteristics of a protocol layer and a channel, whichare required for providing a specific service, and setting therespective detailed parameters and operation methods.

[0030] A broadcast of the system information will now be described.

[0031] The broadcast of the system information is one of major functionof the RRC layer. The system information includes various informationsuch as system information with which the terminal connects to a networkor terminal's mobility support information and measuring information.The system information is transferred through a broadcast controlchannel (BCCH), a logical channel, and can use the BCH or the FACH as atransport channel.

[0032] In order to systematically transmit the system information, theRRC layer constructs a system information block (SIB) by grouping systeminformation with similar characteristics. System information belongingto a different SIB have different characteristics in their transmissionrepetition period as well as in their content. Substantial systeminformation is included in the SIB, while scheduling information fortransmission of the SIB is called on a master information block (MIB) oron a scheduling block (SB).

[0033] The MIB, including reference information or schedulinginformation of SIBs broadcast in a cell, is transmitted regularlythrough the BCH so that the terminal can easily receive the systeminformation.

[0034] Because the MIB includes reference information or schedulinginformation on one or two SBs and the SB includes additional schedulinginformation of SIBs, transmission scheduling information of each SIB canbe obtained through the MIB and the SB.

[0035] The multimedia broadcast/multicast service (MBMS) will now bedescribed.

[0036] The MBMS is a service for transmitting multimedia data such asaudio, video or image data to plural terminals by using auni-directional point-to-multipoint bearer service. The MBMS is dividedinto a broadcast mode and a multicast mode. That is, the MBMS is dividedinto an MBMS broadcast service and an MBMS multicast service.

[0037] The MBMS broadcast mode is a service for transmitting multimediadata to every user in a broadcast area. The broadcast area means abroadcast service available area. One or more broadcast areas may existin one PLMN, one or more broadcast services can be provided in onebroadcast area, and one broadcast service can be provided to severalbroadcast areas.

[0038] The MBMS multicast mode is a service for transmitting multimediadata only to a specific user group existing in a multicast area. Themulticast area means a multicast service available area. One or moremulticast areas can exist in one PLMN, one or more multicast servicescan be provided in one multicast area, and one multicast service can beprovided to several multicast areas.

[0039] In the multicast mode, a user is requested to join a multicastgroup to receive a specific multicast service. At this time, themulticast group refers to a user group that receives the specificmulticast service, and joining refers to a behavior of being admitted tothe multicast group intending for receiving the specific multicastservice.

[0040] An MBMS RB, a radio bearer (RB) for the MBMS, serves to transmituser data of one specific MBMS service transferred from the core networkto UTRAN to a specific terminal group. The MBMS RB is divided into apoint-to-multipoint RB and a point-to-point RB. In order to provide theMBMS service, UTRAN selects one of the two types of MBMS RBs. In orderto select the MBMS RB, UTRAN recognizes the number of users of thespecific MBMS service existing in one cell. UTRAN internally sets athreshold value, and if the number of users existing in a cell issmaller than the threshold value, UTRAN sets the point-to-point MBMS RB,whereas if the number of users existing in a cell is greater than thethreshold value, UTRAN sets the point-to-multipoint MBMS RB.

[0041]FIG. 3 shows one example of a process that UTRAN determines a typeof the MBMS RB.

[0042] In order to transmit specific MBMS service data, UTRAN should setan MBMS RB for a specific MBMS service. For this purpose, UTRANtransmits a group paging signal to terminals which desire to receive thespecific MBMS service (step S1) and initiates a paging timer from atransmission time point. The paging timer is expired when it goes beyonda specific value designated by UTRAN.

[0043] When a terminal, which has received the group paging signal,desires to receive the MBMS service, the corresponding terminaltransmits a paging response signal to UTRAN (step S2). A RRC ConnectionSetup Request message services as the paging response signal. UTRAN canreceive paging response signals from one or more terminals, and receivesthe paging response signal from terminals until the paging timer isexpired.

[0044] When the paging timer is expired, UTRAN counts paging responsesignals received until then, and calculates the number of terminals thatdesire to receive the MBMS service in the corresponding cell (step S3).UTRAN compares the threshold value and the calculated number ofterminals and sets a point-to-multipoint MBMS RB or apoint-to-multipoint MBMS RB.

[0045] For transmission of the MBMS, UTRAN may operate two types oflogical channels for MBMS in each cell: an MBMS control channel (MCCH)and an MBMS traffic channel (MTCH). One MCCH is used to sendMBMS-related control information to one or more terminal groups. OneMTCH is used to send user data of a specific MBMS service to a terminalgroup. There is one-to-one correspondence between an MTCH and an MBMSservice. The point-to-multipoint MBMS RB for a specific MBMS serviceconsists of the MTCH as well as a corresponding transport channel and acorresponding physical channel.

[0046] In the conventional art, common channel configuration informationfor broadcast or multicast are all transferred to the BCCH. That is,UTRAN transmits the system information block (SIB) including commonchannel configuration information through the BCCH regardless of acommon traffic channel (CTCH) and a common control channel (CCCH).Therefore, if this method is applied to the MBMS, the MTCH and the MCCHconfiguration information are all to be transmitted through the BCCH.

[0047] In this respect, however, in the case of the MBMS service,various services are broadcast or multicast, so that the BCCH has toprovide various configurations of MTCH channels. Thus, transmission ofall the MTCH and MCCH data through the BCCH causes the currentconstruction of system information transmitted through the BCCH to bechanged. In the conventional art, in general, the RB is set up by usinga radio bearer setup procedure of the RRC or system information of theRRC.

[0048] In the method of using the radio bearer configuration (setup)procedure, UTRAN transmits a radio bearer setup message for transferringRB setup information to one specific terminal, and then thecorresponding terminal sets up an RB and transmits a radio bearer setupcompletion message to UTRAN.

[0049] Meanwhile, in the method of using system information, a terminalobtains setup information of a specific RB from system informationbroadcast by UTRAN and sets up a corresponding RB.

[0050] The former method is used when one terminal sets up a specificRB, while the latter method is used when one or more terminals sets up aspecific RB. A difference between the two methods is that the formermethod requires a response message of the terminal while the lattermethod does not require a response message of the terminal.

[0051] Accordingly, in case of setting up the MBMS RB by using theformer method is disadvantageous in that radio bearer setup messages inproportion to the number of terminals belong to a terminal group shouldbe transmitted and received, a radio capacity is much taken.

[0052] Thus, setup of the MBMS RB in a method similar to the RB setupthrough the system information is advantageous in terms of the radiocapacity, but no process has been substantially defined for setting upthe MBMS RB.

[0053] The above references are incorporated by reference herein whereappropriate for appropriate teachings of additional or alternativedetails, features and/or technical background.

SUMMARY OF THE INVENTION

[0054] Accordingly, the present invention is directed to method fortransmitting control signal for MBMS data in wireless mobilecommunication system that substantially obviates one or more problemsdue to limitations and disadvantages of the related art.

[0055] An advantage of the present invention is a control signaltransmission method for transmitting system information and MBMS controlinformation through different logical channels.

[0056] Another advantage of the present invention is a control signaltransmission method capable of transmitting radio bearer relatedinformation on a specific service discriminatively by services.

[0057] Another advantage of the present invention is a control signaltransmission method capable of transmitting MBMS-related controlinformation to a dedicated channel-set terminal through a dedicatedcontrol channel (DCCH).

[0058] Another advantage of the present invention is a control signaltransmission method capable of transmitting MBMS-related controlinformation to a common channel-set terminal through an MBMS commoncontrol channel (MCCH).

[0059] Additional advantages and features of the invention will be setforth in part in the description which follows and in part will becomeapparent to those having ordinary skill in the art upon examination ofthe following or may be learned from practice of the invention. Theseand other advantages of the invention may be realized and attained bythe structure particularly pointed out in the written description andclaims hereof, as well as the appended drawings.

[0060] To achieve these and other advantages and in accordance with thepurpose of the invention, as embodied and broadly described herein,there is provided a control signal transmission method in a wirelesscommunication system providing a multimedia broadcast/multicast service(MBMS) to a terminal group including plural terminals, in which systeminformation and control information for an MBMS service are transmittedthrough different logical channels.

[0061] Preferably, the MBMS system information is transmitted through abroadcast control channel (BCCH).

[0062] Preferably, the MBMS system information includes: an MBMS systeminformation block (MBMS SIB) for transmitting MBMS-related systeminformation and a block for transmitting scheduling information on theMBMS SIB.

[0063] Preferably, the MBMS SIB includes setup information of a commoncontrol channel transmitting the MBMS control information.

[0064] Preferably, the MBMS control information is transmitted through alogical channel providing information on one or more MBMS services.

[0065] Preferably, the logical channel is an MBMS common control channel(MCCH).

[0066] Preferably, the MBMS control information includes: an MBMSscheduling block (MSB) and plural MBMS service information blocks(MSIB).

[0067] Preferably, the MSIB includes service-specified information, andthe service-specified information is radio bearer information or setupinformation of an MBMS traffic channel (MTCH).

[0068] Preferably, one MSIB transmits only one service-relatedinformation.

[0069] To achieve at least these advantages in whole or in parts, thereis further provided a control signal transmission method in a wirelesssystem multicasting service data to a terminal group including pluralterminals, including: transmitting system information through a firstlogical channel; transmitting specific service-related controlinformation through a second logical channel; and transmitting aspecific service data through a third logical channel.

[0070] Preferably, the specific service is a multimediabroadcast/multicast service (MBMS).

[0071] Preferably, the first logical channel is a broadcast controlchannel, the second logical channel is an MBMS control channel (MCCH),and the third logical channel is an MBMS traffic channel (MTCH).

[0072] Preferably, the system information includes an MBMS systeminformation block (MBMS SIB) for transmitting MBMS-related systeminformation and a block for transmitting scheduling information on theMBMS SIB.

[0073] Preferably, the MBMS SIB includes setup information of the secondlogical channel transmitting MBMS control information.

[0074] Preferably, the first logical channel provides setup informationof the second logical channel, and the second logical channel providessetup information of the third logical channel.

[0075] Preferably, the service-related control information istransmitted by blocks, and one block transmits only one service-relatedcontrol information.

[0076] Preferably, the service-related control information includes anMBMS scheduling block (MSB) and plural MBMS service blocks (MSIB).

[0077] Preferably, the MSIB includes a service-specified information,and the service-specified information is radio bearer information orsetup information of an MBMS traffic channel (MTCH).

[0078] Preferably, one MSIB transfers only one service-relatedinformation.

[0079] To achieve at least these advantages in whole or in parts, thereis further provided a control signal transmission method in a wirelesssystem transmitting service-related control information to a terminalgroup including plural terminals, in which specific service-relatedcontrol information is transmitted by blocks through a common controlchannel.

[0080] Preferably, the specific service is a multimediabroadcast/multicast service (MBMS).

[0081] Preferably, one block transmits only one service-related controlinformation.

[0082] Preferably, the service-related control information isservice-specified information, and the service-specified information isradio bearer information or setup information of a logical channelproviding information on a specific service.

[0083] Preferably, the logical channel providing information on thespecific service is an MBMS traffic channel (MTCH).

[0084] Preferably, the service-related control information is an MBMSservice information block (MSIB).

[0085] To achieve at least these advantages in whole or in parts, thereis further provided a control signal transmission method in a wirelesscommunication system providing a multimedia broadcast/multicast service(MBMS) to a terminal group including plural terminals, including:constructing MBMS scheduling block (MSB) by services; constructing anMBMS service information block (MSIB); and transmitting the MSB and theMSIB to a terminal group through different logical channels.

[0086] Preferably, the MSB is transmitted through a broadcast controlchannel, and the MSIB is transmitted through an MBMS control channel(MCCH).

[0087] Preferably, the MSIB transmits services by blocks, and one blocktransmits only one service.

[0088] Preferably, the MSIB transmits service-specified information.

[0089] Preferably, the service-specified information is radio bearerinformation or setup information of a logical channel providinginformation on a specific service.

[0090] Preferably, the MSB includes: an MBMS service identifier list;MSIB transmission scheduling information; and MSIB update information.

[0091] Preferably, the transmission scheduling information is a timeindicator such as a system frame number (SFN) indicating time at whichone MSIB is transmitted through a physical channel.

[0092] Preferably, the update information also includes MSIB updateinformation, and is sequentially increased from an initial value to alimit value whenever information of a specific block (i.e. a specificMSIB) is updated, and then set as an initial value.

[0093] Preferably, the MSIB includes: one MBMS service identifier; andradio bearer (RB) configuration (setup) information for a correspondingservice.

[0094] Preferably, the RB setup information includes: time informationat which the MBMS RB is activated; setup information of every channelconstituting the MBMS RB; and setup information of every layer.

[0095] To achieve at least these advantages in whole or in parts, thereis further provided a control signal transmission method in a wirelesscommunication system providing a multimedia broadcast/multicast service(MBMS) to a terminal group including plural terminals, including:receiving system information through a broadcast control channel;obtaining setup information of an MBMS control channel (MCCH) from thesystem information and setting up an MCCH channel; receiving MBMScontrol information through the set MCCH channel; setting up an MBMStraffic channel (MTCH) by using MBMS control information and receivingMBMS data through the MTCH.

[0096] Preferably, the control information receiving step includes:receiving an MBMS scheduling block (MSB); receiving a specific MSIB byusing scheduling information of an MBMS service information block (MSIB)included in the MSB; obtaining setup information of a radio bearer (RB)from the received MSIB; and setting the obtained RB setup information ina terminal and receiving specific MBMS data through the set RB.

[0097] Preferably, the MSIB receives services by blocks, and one blockincludes only one service.

[0098] Preferably, the MSIB transmits a service-specified information,and the service-specified information is radio bearer information orsetup information of a logical channel providing information on aspecific service.

[0099] Preferably, the MSB includes: an MBMS service identifier list;MSIB transmission scheduling information; and MSIB update information.

[0100] Preferably, the transmission scheduling information is a timeindicator such as a system frame number (SFN) indicating time while oneMSIB is transmitted through a physical channel.

[0101] Preferably, the update information also includes MSIB updateinformation, and is sequentially increased from an initial value to alimit value whenever information of a specific block is updated, andthen set as an initial value.

[0102] Preferably, the MSIB includes: one MBMS service identifier; andradio bearer (RB) setup information for a corresponding service.

[0103] Preferably, the RB setup information includes: time informationwhen the MBMS RB is activated; setup information of every channelconstituting the MBMS RB; and setup information of every layer.

[0104] Preferably, the MSIB receiving step includes: receiving an MSBthrough a common control channel; obtaining a block update informationof the MSB and checking whether the MSB has been updated; obtainingtransmission scheduling information and update information of an MSIBfrom a corresponding MSB if the MSB has been updated; checking whetherthe MSIB has been updated by using the update information; and receivinga specific MSIB during a section indicated by the transmissionscheduling information if the MSIB has been updated.

[0105] Preferably, current update information of the MSIB obtained fromthe MSB and previous update information of the MSIB obtained from theMSB are compared, and if the two update information values aredifferent, it is judged that a content of the corresponding MSIB hasbeen updated.

[0106] Preferably, if the two update information values are identical,it is judged that a content of the corresponding MSIB has not beenupdated and an MSIB is not received.

[0107] Preferably, the terminal group can receive a channel other thanthe common control channel for certain time which is not indicated bythe transmission scheduling information, or temporarily stop receivingevery channel.

[0108] To achieve at least these advantages in whole or in parts, thereis further provided a control signal transmission method in a wirelesscommunication system providing a multimedia broadcast/multicast service(MBMS) to a terminal group including plural terminals, whereinMBMS-related control information is transmitted to a terminal, for whicha specific transport channel has been set, through a logical channelcorresponding to the corresponding transport channel.

[0109] Preferably, MBMS-related control information is transmitted to aterminal, for which a dedicated channel has been set, through adedicated control channel (DCCH).

[0110] Preferably, the MBMS-related control information is MBMS trafficchannel (DTCH or MTCH)-related information.

[0111] Preferably, the MBMS-related control information is MBMS radiobearer (RB) re-setup information.

[0112] Preferably, MBMS-related control information is transmitted to aterminal, for which a common channel has been set, through an MBMScontrol channel (MCCH).

[0113] Preferably, the MBMS-related control information is MBMS trafficchannel (MTCH or DTCH)-related information.

[0114] Preferably, the MBMS-related control information is MBMS radiobearer (RB) re-setup information.

[0115] Additional advantages, objects, and features of the inventionwill be set forth in part in the description which follows and in partwill become apparent to those having ordinary skill in the art uponexamination of the following or may be learned from practice of theinvention. The objects and advantages of the invention may be realizedand attained as particularly pointed out in the appended claims.

[0116] It is to be understood that both the foregoing generaldescription and the following detailed description of the presentinvention are exemplary and explanatory and are intended to providefurther explanation of the invention as claimed.

BRIEF DESCRIPTION OF THE DRAWINGS

[0117] The accompanying drawings, which are included to provide afurther understanding of the invention and are incorporated in andconstitute a part of this application, illustrate embodiment(s) of theinvention and together with the description serve to explain theprinciple of the invention.

[0118] In the drawings:

[0119]FIG. 1 illustrates a network structure of general UMTS system;

[0120]FIG. 2 illustrates a structure of a radio access interfaceprotocol between a terminal and UTRAN on the basis of 3GPP radio accessnetwork standards;

[0121]FIG. 3 illustrates a process that UTRAN determines a type of anMBMS radio bearer (RB);

[0122]FIG. 4 illustrates a layer structure of MBMS control informationfor one cell;

[0123]FIG. 5A illustrates that MBMS control information and systeminformation are transmitted through one logical channel (BCCH) inaccordance with a conventional art;

[0124]FIG. 5B illustrates that MBMS control information and systeminformation are transmitted through different logical channels (BCCH andMCCH) in accordance with the present invention;

[0125]FIG. 6 illustrates a method of transmitting and receiving MBMScontrol information and setting up an MBMS RB when a cell initiallyprovides a specific MBMS service;

[0126]FIG. 7 illustrates a first embodiment of resetting an MBMS RB inaccordance with the present invention;

[0127]FIG. 8 illustrates a process that a new terminal sets up an MBMSRB;

[0128]FIG. 9 illustrates a second embodiment of resetting an MBMS RB inwhich when UTRAN recognizes existence of a specific terminal in acorresponding cell, an MBMS RB is reset from a point-to-multipoint to apoint-to-point;

[0129]FIG. 10 illustrates a second embodiment of resetting an MBMS RB inwhich when UTRAN does not recognize existence of a specific terminal ina corresponding cell, an MBMS RB is reset from a point-to-multipoint toa point-to-point;

[0130]FIG. 11 illustrates a method for transmitting newpoint-to-multipoint MBMS RB setup information through the DTCH because aterminal is not able to receive the DTCH and the MCCH simultaneously.

[0131]FIG. 12 illustrates a method for receiving new point-to-multipointMBMS RB setup information through an MCCH if a terminal cansimultaneously receive a DTCH and the MCCH; and

[0132]FIG. 13 illustrates a process of releasing a different MBMS RB.

DETAILED DESCRIPTION OF THE ILLUSTRATED EMBODIMENTS

[0133] Reference will now be made in detail to embodiments of thepresent invention, examples of which are illustrated in the accompanyingdrawings. Wherever possible, the same reference numbers will be usedthroughout the drawings to refer to the same or like parts.

[0134] The present invention is implemented in a mobile communicationsystem such as UMTS (Universal Mobile Telecommunications System)developed by 3GPP. Without being restricted thereto, the presentinvention can be also applied to a communication system operated indifferent standards.

[0135] The present invention proposes a control signal transmissionmethod for transmitting MBMS service data in a wireless system providingvarious types of MBMS services. For this purpose, the present inventionproposes a method for transmitting system information and MBMS controlinformation through different logical channels. That is, the systeminformation is transmitted through a BCCH, while MBMS controlinformation is transmitted through an MCCH.

[0136] The present invention defines construction of MBMS controlinformation transmitted through the MCCH. That is, in the presentinvention, there are constructed an MBMS scheduling block (MSB)consisting of an MBMS service identifier list and scheduling informationof plural MBMS RB configuration (setup) information, and an MBMS serviceinformation block (MSIB) consisting of one MBMS service identifier andMBMS RB setup information for a corresponding service.

[0137] The present invention proposes a method where a terminal groupreceives an MSIB at a certain time indicated by the MSB, sets an MBMS RBby using MBMS RB setup information of the received MBIB, and receivesMBMS service data through the MBMS RB.

[0138] In the present invention, the MSB and the MSIB are repeatedly andcontinuously transmitted to a terminal group. A wireless system (UTRAN)constructs the MSB and the MSIB and then repeatedly and continuouslytransmits the MSB and the MSIB which have the same information. Thewireless system may substitute partial or entire information included inthe MSB and the MSIB with new information.

[0139] The MSB includes block update information that every MSIB has inorder to inform a terminal group that a certain MSIB has been updatedwith new information.

[0140] In addition, in order for the MSB to inform about the update withthe new information, the MSB includes block update information foritself. Accordingly, the MSB also includes update information for eachblock together with an MBMS service identifier list and schedulinginformation of MBMS RB setup information. The block update informationhas a positive integer value. When an initial block is formed, blockupdate information is set as an initial value, and when information of aspecific block is updated, corresponding block update informationincreases to a value obtained by adding 1 to the initial value.Accordingly, whenever information of a specific block is updated, thecorresponding block update information increases to a value obtained byadding 1 to a previous value.

[0141] In a state that an increased value of block update information isidentical to a limit value previously set in the wireless system, ifinformation of a specific block is updated, the corresponding blockupdate information is set as an initial value. Therefore, the value ofthe block update information increases one by one whenever thecorresponding block is updated, continuously circulating between theinitial value and the limit value.

[0142] Construction of system information for MBMS and MBMS controlinformation

[0143] In the present invention, control information for providing anMBMS service, including an MBMS service identifier list and an MBMSservice identifier for transmitting MBMS service data, MBMS radio bearersetup information for each MBMS service, block update information, andscheduling information of MBMS RB setup information, is called MBMScontrol information. That is, the MBMS control information includes anMBMS scheduling block (MSB) and an MBMS service information block(MSIB).

[0144] The MBMS RB setup information includes an activation time wheneach MBMS RB is activated, setup information of channels (logicalchannel, transport channel and physical channel) constituting each MBMSRB and setup information of layers (PDCP layer, RLC layer, MAC layer andphysical layer). The MBMS RB setup information exists for each MBMS RB.Transmission scheduling information of the MBMS RB setup informationprovides time information indicating when one or more MBMS RB setupinformation provided from one cell is respectively transmitted to thephysical channel. For example, when each MBMS RB setup information istransmitted wirelessly through the physical channel, the schedulinginformation informs of a system frame number (SFN) value.

[0145]FIG. 3 illustrates a layer structure of the system information andthe MBMS control information for one cell.

[0146] As shown in FIG. 3, the system information is transmitted througha BCCH, while the MBMS control information is transmitted through anMCCH.

[0147] The control information is roughly divided into an MBMSscheduling block (MSB) and an MBMS service information block (MSIB).

[0148] The MSIB transmits service-specified information (MTCH setupinformation and bearer information), and one block transmits oneservice. The MSIB provides information related one MBMS service providedto a corresponding cell. The MSIB includes an MBMS service identifierand MBMS RB setup information for a corresponding service. The MSIBsexist as many as MBMS services provided in a corresponding cell.

[0149] The MSB includes an MBMS service identifier list provided in acorresponding cell, transmission scheduling information of each MSIB,and block update information for each MSIB. The transmission schedulinginformation of the MSIB indicates certain time when one MSIB istransmitted through the physical channel, which is usually indicated byan SFN value.

[0150] The system information corresponding to an upper position of theMBMS control information includes a master information block (MIB), oneor more system information block (SIB) and an MBMS SIB. The SIB includessubstantial system information, and scheduling information fortransmission of the SIB is carried on the master information block(MIB).

[0151] The MBMS SIB is an SIB transmitting MBMS-related information,that is, MCCH setup information, while the MIB transmits schedulinginformation on the MBMS SIB. For example, the MBMS SIB can existseparately from the conventional SIBs. In this case, the MIB shouldinclude scheduling information on a new SIB (MBMS SIB). For anotherexample, the MBMS SIB may be constructed by adding MCCH setupinformation to one of the conventional SIBs. In this case, because oneof the conventional SIBs is used, there is no new information added tothe MIB and SB.

[0152] In a different embodiment, the MSB may be included in the MBMSSIB. In this case, as for the MSB, an MBMS service identifier listprovided in a corresponding cell, transmission scheduling information ofeach MSIB and block update information for each MSIB are transmittedthrough the BCCH.

[0153] In the present invention, the MBMS control information and thesystem information are transmitted through different logical channels.That is, the system information is transmitted through the BCCH(Broadcast Control Channel), while the MBMS control information istransmitted through the MBMS control channel (MCCH).

[0154] In detail, as shown in FIG. 5A, in the conventional UTRAN, theMBMS control information and system information are transmitted to aterminal through the BCCH, and the terminal receives data through a CTCHafter obtaining setup information (bearer information) of the CTCH fromthe BCCH. Thus, in the conventional art, construction of theMBMS-related control information transmitted through the MCCH is notdefined.

[0155] Comparatively, as shown in FIG. 5B, in the present invention, theUTRAN transmits setup information of the MCCH through the BCCH, andtransmits setup information (bearer information) of the MTCH to theterminal through the MCCH. The terminal obtains the setup information ofthe MTCH from the MCCH, and then receives the MBMS data through theMTCH.

[0156] The MCCH transmits data including one MSB and one or more MSIBsto the terminal group. The terminal group first obtains systeminformation and an MSB through the BCCH and the MCCH, and then, receivesan MSIB including bearer information, that is, the MTCH setupinformation, on a specific service.

[0157] The terminal group receiving the specific MBMS service receivesthe MCCH only for a time interval during which a corresponding MSIB istransmitted by using the scheduling information of MSIBs included in theMSB.

[0158] Accordingly, the terminal belonging to the terminal group canreceive a channel other than the MCCH for some other time than the timesection indicated by the scheduling information of the MSIB. Forexample, the terminal, which can not simultaneously receive pluralchannels, may receive a channel such as a paging channel (PCH), abroadcast channel (BCH) or dedicated control channel (DCCH), a commoncontrol channel (CCCH), a dedicated traffic channel (DTCH), a commontraffic channel (DTCH) or an MTCH (MBMS Traffic Channel). In addition,the terminal may temporarily stop receiving of every channel for someother time than the time section indicated by the scheduling informationof the MSIB, performing a discontinuous reception (DRX).

[0159] The MBMS SIB, MSB and MSIB are repeatedly and continuouslytransmitted. Whether the MBMS SIB, the MSB and MSIB have been updatedcan be known through the block update information, and the MSB has blockupdate information on itself.

[0160] Accordingly, when the terminal first receives the MSB, it storesblock update information for the MSB. Thereafter, the terminal alwaysobtains block update information of the MSB first, and compares thevalue of the obtained block update information with a previously storedvalue.

[0161] If the two values are identical, the terminal judges thatinformation of the corresponding MSB has not been updated. If, however,the two values are different, the terminal judges that information ofthe corresponding MBS has been updated, and checks whether schedulinginformation of the MSIB included in the MSB has been updated.

[0162] The MSB has block update information on every MSIB of one cell.Thus, if the terminal first receives the MSB, or if the terminal judgesthat the information of the MSB has been updated through the aboveprocess, it may obtain block update information on the correspondingMSIB.

[0163] When the terminal first obtains the block update information onthe corresponding MSIB, it stores the corresponding block updateinformation. And then, when the terminal newly obtains block updateinformation later, it compares the newly obtained value with thepreviously stored value. If the two values are identical, the terminaljudges that the information of the corresponding MSIB has not beenupdated and does not receive the corresponding MSIB. If, however, thetwo values are different, the terminal judges that the information ofthe corresponding MSIB has been updated, and receives the correspondingMSIB.

[0164] In the follow-up process, the lower layer includes the PDCP, theRLC, the MAC and the physical layer, the lower layers of the RRC. Thedotted line in the drawing indicates that a process that may beperformed or not according to conditions.

[0165] Setting up MBMS RB for MBMS service

[0166]FIG. 6 shows a method for setting up an MBMS RB by transmittingand receiving MBMS control information when a cell intends to firstprovide a specific MBMS service. In FIG. 6, the arrow indicated by adotted line denotes a step that may not be performed, and the lowerlayer signifies the L1/L2 layer of the terminal or UTRAN.

[0167] The method for setting up MBMS RB is favorably used for settingup the point-to-multipoint MBMS RB. UTRAN recognizes the number ofterminals that desire to receive a specific MBMS service in a cell, andsets a point-to-multipoint or a point-to-point MBMS RB for acorresponding MBMS service depending on whether the number of terminalsis greater than or smaller than a specific threshold value.

[0168] As shown in FIG. 6, in order to provide the specific MBMS serviceto a specific cell, UTRAN RRC performs the above-described operation anddetermines whether to set up the MBMS RB for transmitting user data ofthe specific MBMS service (step S10).

[0169] In this case, one of the following three processes is performeddepending on whether the MBMS control channel (MCCH) has been set ornot.

[0170] If the MCCH has not been set in the corresponding cell, the UTRANRRC transmits MCCH setup information to the lower layer (L1/L2) to setup an MCCH (step S11).

[0171] In this respect, there may already be an MCCH in thecorresponding cell if there is an MBMS RB in the cell in order toprovide some other MBMS service. Therefore, in the case that the MCCHhas been already set up in the cell and a setup condition of the MCCH isdesired to be corrected, the UTRAN RRC transmits MCCH reset informationto the lower layer (L1/L2) to re-setup the MCCH (step S11).

[0172] Finally, if an MCCH has been already set up in the correspondingcell but no re-setup is required, the UTRAN RRC does not perform theMCCH setup/re-setup process.

[0173] The UTRAN RRC transmits MBMS RB setup information for providingthe corresponding MBMS service to the lower layer to set up an MBMS RBin UTRAN (step S12).

[0174] The UTRAN RRC constructs an MBMS SIB including the setupinformation of the MCCH channel provided in the corresponding cell, andtransmits an MIB including scheduling information of the MBMS SIB to theterminal through the BCCH (step S13). At this time, the UTRAN RRCperforms the following operation depending on whether the MIB includesthe scheduling information of the MBMS SIB.

[0175] That is, if the MIB can not include the scheduling information ofthe MBMS SIB in the step of S13, the scheduling information of the MBMSSIB would be transmitted through an SB (step S14). Then, the terminalreceives the SB from UTRAN, and at this time, the scheduling informationof the SB is included in the previously received MIB. Accordingly, theterminal obtains the scheduling information of the SB from thepreviously received MIB and receives the corresponding SB.

[0176] If, however, the MIB includes the scheduling information of theMBMS SIB in the step of S13, the terminal does not receive the SB.

[0177] After the step S13 or S14 is completed, the UTRAN RRC transmitsthe MBMS SIB to the terminal group of the corresponding cell through theBCCH (step S15). Then, the terminal receives the MBMS SIB by using thescheduling information of the MBMS SIB included in the MIB or SB.

[0178] After receiving the MBMS SIB, the RRC of the terminal belongingto the terminal group transmits the MCCH setup information included inthe MBMS SIB to the lower layer to set up the MCCH in the terminal (stepS16).

[0179] Thereafter, the UTRAN RRC constructs one MSIB for thecorresponding MBMS service and then constructs scheduling information ofthe MSIB. The UTRAN RRC transmits the MSB including the MSIB schedulinginformation to a specific terminal group through the MCCH (step S17),and the terminal RRC obtains the scheduling information of a specificMSIB from the received MSB and then receives a specific MSIB accordingto the corresponding scheduling information (step S18). At this time,the terminal group does not receive unnecessary MSIB. That is, theterminal group receiving the specific MBMS service does not receiveother MSIB than the specific MSIB for the corresponding MBMS service.

[0180] The terminal RRC belonging to the terminal group obtains MBMS RB(MTCH or DTCH) setup information for the specific MBMS service from thereceived MSIB, and transmits the obtained setup information to the lowerlayer to set up the MBMS RB (step 19).

[0181] If data is received from an upper layer of the user plane afteran activation time included in the MBMS RB setup information of thereceived MSIB, the UTRAN lower layer transmits user data of thecorresponding MBMS service to the specific terminal group through theMBMS RB (step S20). At this time, in case of thepoint-to-multipoint(PTM) MBMS RB, the logical channel (MTCH) is used forthe data transmission, while in case of the point-to-point(PTP) MBMS RB,the logical channel (DTCH) is used for data transmission. The lowerlayer of the terminal belonging to the corresponding terminal groupreceives the user data transmitted from the MBMS RB after the activationtime included in the MBMS RB setup information, and the received data istransmitted to the upper layer of the user plane of the lower layer ofthe terminal.

[0182] First embodiment of re-setting MBMS RB

[0183] In general, the existing MBMS RB can be re-set due to change in aservice transfer rate and a packet size. In the present invention, theprocess of re-setting a certain MBMS RB for a specific MBMS service toan MBMS RB with a new setup value. This process is favorably performedfor re-setting a point-to-multipoint MBMS RB to a point-to-multipointMBMS RB.

[0184]FIG. 7 illustrates the first embodiment of the resetting the MBMSRB, in which the setup of MCCH is not changed in the process ofresetting a specific MBMS RB. If the previous setup of the MCCH ischanged according to the resetting of the MBMS, the terminal and UTRANperform the same process as that of FIG. 6, and in this case, theprocess of setup of the MCCH and the MBMS RB is replaced with theresetting the MCCH and the MBMS RB.

[0185] As shown in FIG. 7, when a change in a transfer rate and packetsize of an MBMS service is detected, the UTRAN RRC first determinesre-setup of the MBMS RB (step S21). At this time, the UTRAN RRC cantemporarily stop data transmission in order to prevent a data loss.

[0186] The UTRAN RRC transmits re-setup information of the MBMS RB tothe lower layer, to re-set up an MBMS RB in UTRAN (step S22). And then,the UTRAN RRC substitutes the existing MBMS RB setup information of theMSIB on the corresponding MBMS service with the MBMS RB re-setupinformation. After constructing scheduling information of the MSIB, theUTRAN RRC transmits an MSB including MSIB scheduling information to theterminal group (step S23).

[0187] The terminal first receives the MSB to detect whether the MSB hasbeen updated. If the MSB has been updated, the terminal compares thevalue of block update information on the corresponding MSIB with apreviously stored value. If the two values are different, the terminalobtains scheduling information of the corresponding MSIB.

[0188] The UTRAN RRC transmits the MSIB according to the schedulinginformation of the MSIB (step S24). The terminal receives the specificMSIB according to the previously obtained scheduling information. Atthis time, the terminal group does not receive any unnecessary MSIB.That is, a terminal group which receives a specific MBMS service doesnot receive any other MSIB than the specific MSIB for the correspondingMBMS service.

[0189] The RRC of the terminal belonging to the terminal obtains theMBMS RB re-setup information for the specific MBMS service from thereceived MSIB, and transmits the obtained re-setup information to thelower layer to re-set up the MBMS RB (step S25).

[0190] After an activation time included in the MBMS RB re-setupinformation of the received MSIB, if the UTRAN lower layer receives datafrom the upper layer of the user plane or resumes data transmissionwhich has been temporarily suspended, it transmits the user data of thecorresponding MBMS service to a specific terminal group through the MBMSRB. At this time, in case of the point-to-multipoint MBMS RB, thelogical channel (MTCH) is used, whereas in case of thepoint-to-multipoint MBMS RB, the DTCH is used for data transmission. Thelower layer of the terminal belonging to the corresponding terminalgroup receives the user data from the MBMS RB after the activation timeincluded in the MBMS RB setup information (step S26), and the receiveddata is transmitted to the upper layer of the user plane.

[0191] In general, when a terminal is moved into a new cell, an MBMS RBof the new cell should be set up in order to receive a specific MBMSservice that the terminal has received in the previous cell. Inaddition, in a state that the specific MBMS service is already providedin a cell, if a new terminal joins a terminal group to receive data, theMBMS RB should be set up.

[0192] The process that, after a setup of an MBMS RB, a new terminalsets the previously set MBMS RB therein to receive data of an MBMSservice, will now be described.

[0193]FIG. 8 shows a process that a new terminal sets up an MBMS RB.

[0194] The process of FIG. 8 is the same as the steps S13˜S20 of FIG. 6.That is, the new terminal first receives an MIB or an SB of acorresponding cell through the BCCH to obtain an MBMS SIB, and sets upan MCCH therein (steps S30-S33). In addition, the new terminal receivesan MSB transmitted through the MCCH to obtain an MSIB for the MBMSservice desired to be received by a user, and sets up an MBMS RB therein(steps S34-S36).

[0195] The terminal receives the MBMS data from the MBMS RB (MTCH orDTCH) after an activation time included in the MBMS RB setup informationof the MSIB (step S37), and transmits it to the upper layer of the userplane of the lower layer. At this time, in case of thepoint-to-multipoint MBMS RB, the logical channel (MTCH) is used for datatransmission, while incase of the point-to-point MBMS RB, the DTCH isused. There is a possibility that the MBMS RB of UTRAN is alreadytransmitting a data. In this case, the activation time may not beincluded in the MBMS RB setup information. If the activation time is notincluded in the MBMS RB setup information, the terminal receives theMBMS RB immediately after the MBMS RB is set up.

[0196] Second embodiment of re-setup of MBMS RB: re-setup frompoint-to-multipoint MBMS RB to point-to-point MBMS RB

[0197] The present invention proposes a method for re-setting up apoint-to-multipoint MBMS RB for a specific MBMS service to apoint-to-point MBMS RB with a new setup value. For this purpose, in thepresent invention, MBMS-related control information, that is, MBMS RBre-setup information, is transmitted to a terminal, for which a commonchannel has been set, through a current MBMS common control channel(MCCH), not the DCCH.

[0198] The general re-setup process of the MBMS RB with respect to FIG.7 (the first embodiment of the re-setup of MBMS RB) can be used forre-setting up from the point-to-multipoint MBMS RB to the point-to-pointMBMS RB, but the re-setup process of FIG. 7 is favorable for re-settingup again the point-to-multipoint MBMS RB to the point-to-multipoint MBMSRB.

[0199] The second embodiment of the re-setup of the MBMS RB is differentfrom the first embodiment of the re-setup of the MBMS RB, in the aspectthat the point-to-point MBMS RB is set up by using the radio bearer (RB)setup or radio bearer re-setup process. The RB setup/re-setup requires aresponse of the terminal, so that a point-to-point RB can be reliabilityreleased.

[0200] In the second embodiment of the re-setup of the MBMS RB includestwo cases depending on whether UTRAN recognizes existence of a specificterminal in a cell.

[0201]FIG. 9 illustrates a process of re-setup of MBMS RB from apoint-to-multipoint to a point-to-point in case that UTRAN recognizes anexistence of a terminal in a cell.

[0202] As shown in FIG. 9, UTRAN transmits MBMS data through apoint-to-multipoint MBMS RB (step S40). At this time, the logicalchannel MTCH is used for the data transmission and reception.

[0203] UTRAN RRC recognizes the number of users who receive the specificMBMS service in a corresponding cell and determines re-setup of the MBMSRB (step S41). For example, UTRAN RRC detects a cell movement of aspecific terminal through a cell update procedure. At this time, theUTRAN RRC calculates the number of users who are receiving the specificMBMS service in the cell. If the number of users is smaller than aspecific threshold value, the UTRAN RRC determines to re-setup the MBMSRB from the point-to-multipoint to the point-to-point. In order tore-setup the MBMS RB, UTRAN can temporarily stop data transmission ofthe corresponding MBMS service.

[0204] UTRAN RRC transmits the point-to-point MBMS RB setup informationto the lower layer to set up the point-to-point MBMS RB in UTRAN (stepS42). Because the point-to-point MBMS RB is a dedicated channel for aspecific terminal, its information may differ for every terminal. Thus,the point-to-point MBMS RBs for specific MBMS services are provided asmany as terminals belonging to a specific terminal group receiving theservice. For this reason, UTRAN should transmit the MBMS RB setupinformation as many as the point-to-point MBMS RBs to the lower layer ofUTRAN.

[0205] The UTRAN RRC transmits the point-to-point MBMS RB setupinformation to every RRC of terminals belonging to the specific terminalgroup through the MCCH (step S43). At this time, the point-to-point MBMSRB setup information is inserted in an RRC RB setup message andtransmitted to each terminal. Accordingly, the terminal RRC reconstructsthe MBMS RB from the point-to-multipoint to the point-to-point on thebasis of the received point-to-point MBMS RB setup information (stepS44).

[0206] That is, when the RRC RB setup message is received, the RRC ofthe terminal belonging to the terminal group commands the lower layer ofthe terminal to release the point-to-multipoint MBMS RB in order torelease the point-to-multipoint MBMS RB for receiving the MBMS service,and transmits the received point-to-point MBMS RB setup information tothe lower layer of the terminal to set up the point-to-point MBMS RB.

[0207] After the setup of the lower layer is completed, the terminal RRCinserts a point-to-point MBMS RB setup completion information into anRRC RB setup completion message and transmits it to the UTRAN RRC. Uponreceiving the RRC RB setup completion message, the UTRAN RRC commandsthe lower layer of UTRAN to release the point-to-multipoint MBMS RB.

[0208] Then, the L1/L2 of UTRAN resumes data transmission of the MBMSservice through the new point-to-point MBMS RB including the logicalchannel (DTCH) (step S45).

[0209]FIG. 10 illustrates a process of re-setup of MBMS RB frompoint-to-multipoint to point-to-point if UTRAN does not recognizeexistence of a terminal in a cell.

[0210] As shown in FIG. 10, a terminal is currently receiving MBMS datathrough the point-to-multipoint MBMS RB (step S50). At this time, thelogical channel MTCH is used for data transmission and reception.

[0211] The UTRAN RRC detects a cell movement of a terminal through acell update procedure, and calculates the number of users who arereceiving a specific MBMS service in the corresponding cell. If thecalculated number of users is smaller than a specific threshold value,the UTRAN RRC determines re-setup of the MBMS RB frompoint-to-multipoint to point-to-point (step S51).

[0212] The UTRAN RRC substitutes existing MBMS RB setup information ofan MSIB for the corresponding MBMS service with the MBMS RB re-setupinformation. The UTRAN RRC constructs scheduling information of theMSIB, and then transmits an MSB including the MSIB schedulinginformation to a specific terminal group through the MCCH (step S52).

[0213] The terminal receives the MSB and checks whether the MSB has beenupdated. If the MSB has been updated, the terminal compares a value ofblock update information on the corresponding MSIB with a previouslystored value.

[0214] If the two values are different, the terminal obtains schedulinginformation of the corresponding MSIB. The UTRAN RRC adds apoint-to-multipoint MBMS RB re-setup notification message in the MSIBfor the MBMS service and transmits it to the terminal group (step S53).

[0215] Accordingly, the terminal RRC reconstructs the MBMS RB frompoint-to-multipoint to point-to-point on the basis of the receivedpoint-to-multipoint MBMS RB re-setup notification (step S54).

[0216] In other words, the terminal RRC receives the MSIB for thecorresponding MBMS service by using the scheduling information andobtains the point-to-multipoint MBMS RB setup notification message. Themessage informs that terminals of the corresponding terminal groupshould re-set up the MBMS RB from the point-to-point topoint-to-multipoint.

[0217] When the point-to-multipoint MBMS RB setup notification messageis obtained, the RRCs of the terminals belonging to the terminal grouprespectively transmit an MBMS RB re-setup request message to the UTRANRRC. The message includes terminal identifier information ofcorresponding terminals.

[0218] The UTRAN RRC transmits the point-to-point MBMS RB setupinformation to the lower layer of UTRAN, to set up the point-to-pointMBMS RB in UTRAN. Because the point-to-point MBMS RB is a dedicatedchannel for a specific channel, UTRAN transmits MBMS RB setupinformation as many as the point-to-point MBMS RBs to the lower layer ofUTRAN.

[0219] In addition, the URTAN RRC transmits the point-to-point MBMS RBsetup information to every RRC of terminals belonging to the specificterminal group in the cell. At this time, the point-to-point MBMS RBsetup information is inserted in the RRC RB message and transmitted toeach terminal.

[0220] Upon receiving the RRC RB setup message, the RRC of the terminalbelonging to the terminal group commands the lower layer of the terminalto release the point-to-multipoint MBMS RB in order to release thepoint-to-multipoint MBMS RB for receiving the MBMS service, andtransmits the received point-to-point MBMS RB setup information to thelower layer of the terminal in order to set up the point-to-point MBMSRB.

[0221] After the setup of the lower layer is completed, the terminal RRCinserts point-to-point MBMS RB setup completion information into an RRCRB setup completion message and transmits it to the UTRAN RRC. Uponreceiving the RRC RB setup completion message, the UTRAN RRC commandsthe lower of UTRAN to release the point-to-multipoint MBMS RB.

[0222] Accordingly, UTRAN resumes data transmission of the MBMS servicethrough the new point-to-point MBMS RB including the logical channel(DTCH) (step S55).

[0223] A third embodiment of re-setup of MBMS RB: re-setup frompoint-to-point MBMS RB to point-to-multipoint MBMS RB

[0224] The present invention proposes a method for re-setting up acertain point-to-point MBMS RB for a specific MBMS service to apoint-to-multipoint MBMS RB having a new setup value. For this purpose,in the present invention, MBMS-related control information, that is,MBMS RB re-setup information, is transmitted to a terminal, for which adedicated channel has been set, through a current dedicated controlchannel (DCCH), not the MCCH.

[0225] The general re-setup process of the MBMS RB with respect to FIG.8 (the first embodiment of the re-setup of MBMS RB) can be used forre-setting up from the point-to-multipoint MBMS RB to the point-to-pointMBMS RB, but the re-setup process of FIG. 7 is favorable for re-settingup again the point-to-multipoint MBMS RB to the point-to-multipoint MBMSRB.

[0226] In the third embodiment of re-setup of MBMS RB, a point-to-pointMBMS RB is released by using the same process of RB setup or RB re-setupas in the second embodiment. The reason is that the RB setup/re-setuprequires a terminal's response, a point-to-point RB can be releasedreliably.

[0227] The third embodiment of the re-setup of MBMS RB includes twocases depending on whether a terminal can simultaneously receive theDTCH and the MCCH.

[0228]FIG. 11 illustrates a method for transmitting newpoint-to-multipoint MBMS RB setup information through the DTCH because aterminal is not able to receive the DTCH and the MCCH simultaneously.

[0229] As shown in FIG. 11, UTRAN transmits MBMS data through thepoint-to-point MBMS RB (step S70). At this time, the logical channelDTCH is used for data transmission and reception.

[0230] The UTRAN RRC detects a cell movement of a specific terminalthrough a cell update procedure, and calculates the number of users whoare receiving a specific MBMS service in a corresponding cell. If thenumber of users is smaller than a specific threshold value, the UTRANRRC determines re-setup of MBMS RB from the point-to-multipoint topoint-to-point (step S71). At this time, UTRAN may temporarily stop datatransmission of the corresponding MBMS service in order to re-set up theMBMS RB.

[0231] The UTRAN RRC sets up the point-to-multipoint MBMS RB at thelower layer (L1/L2) of UTRAN (step S72), and transmits thepoint-to-multipoint MBMS RB setup information to every RRC of terminalsbelonging to a specific terminal group in the cell (step S73). At thistime, point-to-multipoint MBMS RB setup information is inserted into anRRC RB setup message and transmitted to each terminal. Thepoint-to-multipoint MBMS RB setup information is the same to everyterminals belonging to the specific terminal group.

[0232] Then, the terminal RRC reconstructs the MBMS RB from thepoint-to-point to the point-to-multipoint on the basis of the receivedpoint-to-multipoint MBMS RB setup information (step S74).

[0233] That is, when the point-to-multipoint MBMS RB setup informationis received, the RRCs of terminals belonging to the terminal groupcommand the lower layer to release the point-to-point MBMS RB in orderto release the point-to-point MBMS RB, and transmit the receivedpoint-to-multipoint MBMS RB setup information to the lower layer of theterminal in order to set up the point-to-multipoint MBMS RB.

[0234] After the setup of the lower layer is completed, the terminal RRCinserts a point-to-multipoint MBMS RB setup completion information intoan RRC RB setup completion message and transmits it to the UTRAN RRC.Upon receiving the RRC RB setup completion message, the UTRAN RRCcommands the lower layer of UTRAN to release the point-to-point MBMS RB.At this time, the point-to-point MBMS RB is a dedicated channel for aspecific terminal, the UTRAN RRC should transmit the MBMS RB releasecommand as many as the point-to-point MBMS RBs to the lower layer ofUTRAN.

[0235] Accordingly, the UTRAN RRC resumes of data transmission of theMBMS service through the new point-to-point MBMS RB including thelogical channel (DTCH) (step S75).

[0236]FIG. 12 illustrates a method for receiving new point-to-multipointMBMS RB setup information through the MCCH if the terminal is able tosimultaneously receive the DTCH and the MCCH. In this process, it isassumed that the MCCH has been already set for UTRAN and the terminal.

[0237] As shown in FIG. 12, a terminal is receiving data through thepoint-to-point MBMS RB (step S80), and the logical channel DTCH is usedfor the data transmission and reception.

[0238] The UTRAN RRC detects a cell movement of a specific terminalthrough the cell update procedure, and calculates the number of userswho are receiving a specific MBMS service in a cell. If the number ofusers is smaller than a specific threshold value, the UTRAN RRCdetermines re-setup of MBMS RB from the point-to-multipoint topoint-to-point (step S81). At this time, UTRAN may temporarily stop datatransmission of a corresponding MBMS service to re-set up the MBMS RB.

[0239] The UTRAN RRC transmits the point-to-multipoint MBMS RB setupinformation to the lower layer (L1/L2) of UTRAN, to set up thepoint-to-multipoint MBMS RB in UTRAN (step S82). In addition, the UTRANRRC transmits MBMS control information, that is, an MSB and an MSIN,through the MCCH (steps S83 and S84).

[0240] The terminal first receives the MSB and checks whether the MSBhas been updated. If the MSB has been updated, the terminal compares avalue of block update information on the corresponding MSIB with apreviously stored value. If the two values are different, the terminalobtains scheduling information of the corresponding MSIB.

[0241] After obtaining the scheduling information of the specific MSBIfrom the received MSB, the terminal receives a specific MSIB accordingto the scheduling information. At this time, the terminal group does notreceive unnecessary MSIB. That is, a terminal group receiving a specificMBMS service does not receive any other MSIB than the specific MSBI forthe corresponding MBMS service.

[0242] Then, the terminal RRC reconstructs the MBMS RB from thepoint-to-point to point-to-multipoint by using the update information ofthe received MSB and the scheduling information of the MSIB (step S85).

[0243] In other words, the RRC of the terminal belonging to the terminalgroup obtains MBMS RB setup information for the specific MBMS serviceform the received MSIB and commends the lower layer to release thepoint-to-point MBMS RB in order to release the point-to-point MBMS RB,and transmits the obtained point-to-multipoint MBMS RB setup informationto the lower layer of the terminal in order to set up thepoint-to-multipoint MBMS RB.

[0244] When the setup of the lower layer is completed, the terminal RRCinserts point-to-point MBMS RB setup completion information into an RRCRB setup completion message and transmits it to the UTRAN RRC.

[0245] Upon receiving the RRC RB setup completion message, the UTRAN RRCcommands the lower layer of UTRAN to release the point-to-point MBMS RB.At this time, the point-to-point MBMS RB is a dedicated channel for aspecific terminal, the UTRAN RRC should transmit MBMS RB release commandas many as the point-to-point MBMS RBs to the lower layer of UTRAN.

[0246] Accordingly, after an activation time included in the MBMS RBre-setup information of the received MSIB, if the UTRAN lower layerreceives data from the upper layer of the user plane or resumes datatransmission which has been temporarily suspended, it transmits thecorresponding MBMS data to the specific terminal group through thepoint-to-multipoint MBMS RB (step S86). The lower layer of the terminalbelonging to the corresponding terminal group receives the MBMS datatransmitted form the MBMS RB after the activation time included in theMBMS RB setup information and transmits it to the upper layer of theuser plane of the lower layer of the terminal.

[0247] Release of MBMS RB

[0248]FIG. 13 illustrates a process of releasing a different MBMS RB.

[0249] The process of FIG. 13 can be applied both to release of thepoint-to-multipoint MBMS RB and to the point-to-point MBMS RB. The MBMSRB can be released by using the radio bearer releasing process of theconventional art, but the problem of the conventional art is that everyterminal belonging to a specific terminal group should transmit aresponse message to UTRAN.

[0250] A terminal first receives an MSB from the UTRAN RRC and checkswhether the MSB has been updated (step S90). If the MSB has beenupdated, the terminal compares a value of block update information onthe corresponding MSIB with a previously stored value. If the two valuesare different, the terminal obtains scheduling information of thecorresponding MSIB.

[0251] The terminal receives a specific MSIB according to the schedulinginformation (step S91). At this time, a terminal group does not receivean unnecessary MSIB. That is, a terminal group which receives a specificMBMS service does not receives any other MSIB than the specific MSIB forthe corresponding MBMS service. The MSIB includes an MBMS RB releasecommand for the specific MBMS service.

[0252] The RRC of the terminal belonging to the terminal group obtainsMBMS RB release information for the specific MBMS service from thereceived MSIB. The terminal RRC commands the lower layer of the terminalto release the MBMS RB (step S92), and the UTRAN RRC commands the lowerlayer of UTARN to release the MBMS RB (step S93).

[0253] As so far described, in the case of the MBMS RB, a method isrequired for setting up a specific RB for terminal groups. In case ofsetting up an MBMS RB by using the conventional radio bearer setup,messages should be transmitted and received as many as the usersbelonging to a terminal group, causing a problem that a radio capacityis much occupied.

[0254] Therefore, it is advantageous in the aspect of the radio capacitythat the MBMS RB is set up in the similar manner of the RB setup throughthe system information. In addition, in the present invention, the MBMScontrol information is positioned at a lower position of the systeminformation, so as to be easily applied when the MBMS is newly updatedfor an existing system.

[0255] It will be apparent to those skilled in the art that variousmodifications and variations can be made in the present invention. Thus,it is intended that the present invention covers the modifications andvariations of this invention provided they come within the scope of theappended claims and their equivalents.

What is claimed is:
 1. A method of receiving by a wireless userequipment a multicast/broadcast service comprising: configuring adedicated control channel for receiving a user specific controlinformation by the user equipment; and receiving a multicast/broadcastservice control information for point-to-multipoint data transmission bythe user equipment through the configured dedicated control channel. 2.A method of transmitting a multicast/broadcast service to a wirelessuser equipment comprising: configuring a dedicated control channel forsending a user specific control information to the user equipment; andsending a multicast/broadcast service control information forpoint-to-multipoint data transmission to the user equipment by the radioaccess network through the configured dedicated control channel.
 3. Amethod of receiving by a wireless user equipment a multicast/broadcastservice comprising: receiving an multicast/broadcast service controlinformation by the user equipment through a dedicated control channeland receiving multicast/broadcast service by the user equipment througha dedicated traffic channel; and receiving a transition indication frompoint-to-point to point-to-multipoint through the dedicated controlchannel.
 4. A method according to claim 3, further comprising receivingan multicast/broadcast service control information by the user equipmentthrough the dedicated control channel and receiving multicast/broadcastservice by the user equipment through a multicast traffic channel.
 5. Amethod according to claim 3, wherein the transition indication includesinformation on point-to-multipoint traffic channel configuration.
 6. Amethod of receiving by a wireless user equipment a multicast/broadcastservice comprising: receiving an multicast/broadcast service controlinformation by the user equipment through a multicast/broadcast controlchannel and receiving multicast/broadcast service by the user equipmentthrough a multicast traffic channel; and receiving a transitionindication from point-to-multipoint to point-to-point through themulticast/broadcast control channel.
 7. A method according to claim 6,further comprising receiving an multicast/broadcast service controlinformation by the user equipment through the multicast/broadcastcontrol channel and receiving multicast/broadcast service by the userequipment through a dedicated traffic channel.
 8. A method according toclaim 6, wherein the transition indication includes information onpoint-to-point traffic channel configuration.
 9. A method oftransmitting from a radio access network a multicast/broadcast servicecomprising: sending an multicast/broadcast service control informationto the user equipment through a dedicated control channel and sendingmulticast/broadcast service to the user equipment through a dedicatedtraffic channel; and sending a transition indication from point-to-pointto point-to-multipoint through the dedicated control channel.
 10. Amethod according to claim 9, wherein the radio access network sends thetransition indication to other user equipments through amulticast/broadcast control channel.
 11. A method according to claim 10,wherein the radio access network sends the transition indication toother user equipments through a multicast/broadcast control channelsimultaneously with the sending of the transition indication to the userequipment through the dedicated control channel.
 12. A method accordingto claim 9, further comprising sending an multicast/broadcast servicecontrol information to the user equipment through the dedicated controlchannel and sending multicast/broadcast service to the user equipmentthrough a multicast traffic channel.
 13. A method according to claim 9,wherein the transition indication includes information onpoint-to-multipoint traffic channel configuration.
 14. A method ofsending by a radio access network a multicast/broadcast servicecomprising: sending a multicast/broadcast service control information tothe user equipment through a multicast/broadcast control channel andsending multicast/broadcast service to the user equipment through amulticast traffic channel; and sending a transition indication frompoint-to-multipoint to point-to-point through the multicast/broadcastcontrol channel.
 15. A method according to claim 14, further comprisingsending a multicast/broadcast service control information to the userequipment through the multicast/broadcast control channel and sendingmulticast/broadcast service to the user equipment through a dedicatedtraffic channel.
 16. A method according to claim 14, wherein thetransition indication includes information on point-to-point trafficchannel configuration.
 17. A method according to claim 14, wherein theradio access network sends the transition indication to other userequipments through a dedicated control channel.
 18. A method accordingto claim 17, wherein the radio access network sends the transitionindication to other user equipments through a dedicated control channelsimultaneously with the sending of the transition indication to the userequipment through the multicast/broadcast control channel.
 19. A methodof receiving by a wireless user equipment a multicast/broadcast servicecomprising: receiving a first configuration information through a firstchannel; receiving a second configuration information through a secondchannel after receiving the first configuration information, wherein thefirst configuration information contains information for receiving thesecond configuration information; and receiving the multicast/broadcastservice through a third channel after receiving the second configurationinformation, wherein the second configuration information containsinformation for receiving the multicast/broadcast service.
 20. Themethod of claim 19, wherein the first channel is a broadcast channel.21. The method of claim 19, wherein the second channel is a controlchannel for multicast/broadcast service.
 22. The method of claim 19,wherein the third channel is a traffic channel for multicast/broadcastservice.
 23. The method of claim 22, wherein the traffic channel isdedicated for a specific multicast/broadcast service.
 24. The method ofclaim 19, wherein the first configuration information containsinformation on the second channel.
 25. The method of claim 19, whereinthe second configuration information contains information on the thirdchannel.
 26. The method of claim 19, wherein the user equipment receivesthe multicast/broadcast service without having responded to a UTRAN. 27.The method of claim 19, wherein the user equipment joined the multicastservice.
 28. A method of receiving an multicast/broadcast service usingthree different channels, where a first channel provides information ona second channel and the second channel provides information on a thirdchannel, the multicast/broadcast service being provided on the thirdchannel, the first channel being a broadcast channel, the second channelbeing a control channel and the third channel being a traffic channeldedicated for the multicast/broadcast service.
 29. A method of receivingby a wireless user equipment a multicast/broadcast service comprising:receiving an multicast/broadcast service information block containing amulticast/broadcast service specific control information, themulticast/broadcast service information block being dedicated to asingle multicast/broadcast service; and receiving the singlemulticast/broadcast service based on the received multicast/broadcastservice information block.
 30. The method according to claim 29, furthercomprising repeating the multicast/broadcast service information block.31. The method according to claim 29, wherein the multicast/broadcastservice information block is received at a scheduled time.
 32. Themethod according to claim 29, further comprising receiving a schedulingblock prior to receiving the multicast/broadcast service informationblock, the scheduling block including information on when the userequipment should receive the multicast/broadcast service informationblock.
 33. The method according to claim 32, wherein the user equipmentreceives information on when the user equipment should receive thescheduling block through BCCH.
 34. The method according to claim 33,wherein the information on when the user equipment should receive thescheduling block is received through an multicast/broadcast servicesystem information block.
 35. The method according to claim 32, whereinthe scheduling block is received periodically through a common channel.36. The method according to claim 35, wherein the common channel is oneof MCCH and BCCH.
 37. The method according to claim 32, wherein thescheduling block includes information on whether the multicast/broadcastservice information block is updated.
 38. The method according to claim37, wherein the user equipment receives the multicast/broadcast serviceinformation block based on the information on whether themulticast/broadcast service information block is updated.
 39. The methodaccording to claim 32, wherein the scheduling block includes an updatetag, the update tag indicating whether the multicast/broadcast serviceinformation block is updated.
 40. The method according to claim 29,wherein the user equipment has joined the multicast/broadcast service.41. The method according to claim 29, wherein the user equipmentreceives a specific multicast/broadcast service information block thatthe user equipment desires.
 42. The method according to claim 29,wherein the user equipment receives the multicast/broadcast servicebased on the multicast/broadcast service information block.
 43. Themethod according to claim 29, wherein the multicast/broadcast serviceinformation block is received through MCCH.
 44. The method according toclaim 29, further comprising receiving a scheduling block prior toreceiving the multicast/broadcast service information block, thescheduling block including information on when the user equipment shouldreceive the multicast/broadcast service information block, thescheduling block and the multicast/broadcast service information blockare received by the user equipment through a same common channel. 45.The method according to claim 44, wherein the same common channel isMCCH.
 46. A method of receiving by a wireless user equipment amulticast/broadcast service comprising: receiving an multicast/broadcastservice system information block; receiving a scheduling block, themulticast/broadcast service system information block includinginformation on when the user equipment should receive the schedulingblock; and receiving an multicast/broadcast service information blockcontaining a multicast/broadcast service specific control information,the multicast/broadcast service information block being dedicated to asingle multicast/broadcast service, the scheduling block includinginformation on when the user equipment should receive themulticast/broadcast service information block.
 47. A method of receivingby a wireless user equipment a multicast/broadcast service comprising:receiving an multicast/broadcast service system information block; andreceiving an multicast/broadcast service information block containing amulticast/broadcast service specific control information, themulticast/broadcast service information block being dedicated to asingle multicast/broadcast service, the multicast/broadcast servicesystem information block including information on when the userequipment should receive the multicast/broadcast service informationblock.